mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-21 18:29:46 +00:00
Use canonical forms for the branch probability zero heutistic.
- Drop support for X >u 0, it's equivalent to X != 0 and should be canonicalized into the latter. - Add X < 1 -> unlikely, which is what instcombine canonicalizes X <= 0 into. - Add X > -1 -> likely, which is what instcombine canonicalizes X >= 0 into. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139110 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
parent
fec0c6fa56
commit
26eb870d7e
@ -289,37 +289,42 @@ bool BranchProbabilityAnalysis::calcZeroHeuristics(BasicBlock *BB) {
|
||||
|
||||
Value *RHS = CI->getOperand(1);
|
||||
ConstantInt *CV = dyn_cast<ConstantInt>(RHS);
|
||||
if (!CV || !CV->isZero())
|
||||
if (!CV)
|
||||
return false;
|
||||
|
||||
bool isProb;
|
||||
switch (CI->getPredicate()) {
|
||||
case CmpInst::ICMP_EQ:
|
||||
// Equal to zero is not expected to be taken.
|
||||
if (CV->isZero()) {
|
||||
switch (CI->getPredicate()) {
|
||||
case CmpInst::ICMP_EQ:
|
||||
// X == 0 -> Unlikely
|
||||
isProb = false;
|
||||
break;
|
||||
case CmpInst::ICMP_NE:
|
||||
// X != 0 -> Likely
|
||||
isProb = true;
|
||||
break;
|
||||
case CmpInst::ICMP_SLT:
|
||||
// X < 0 -> Unlikely
|
||||
isProb = false;
|
||||
break;
|
||||
case CmpInst::ICMP_SGT:
|
||||
// X > 0 -> Likely
|
||||
isProb = true;
|
||||
break;
|
||||
default:
|
||||
return false;
|
||||
}
|
||||
} else if (CV->isOne() && CI->getPredicate() == CmpInst::ICMP_SLT) {
|
||||
// InstCombine canonicalizes X <= 0 into X < 1.
|
||||
// X <= 0 -> Unlikely
|
||||
isProb = false;
|
||||
break;
|
||||
|
||||
case CmpInst::ICMP_NE:
|
||||
// Not equal to zero is expected.
|
||||
} else if (CV->isAllOnesValue() && CI->getPredicate() == CmpInst::ICMP_SGT) {
|
||||
// InstCombine canonicalizes X >= 0 into X > -1.
|
||||
// X >= 0 -> Likely
|
||||
isProb = true;
|
||||
break;
|
||||
|
||||
case CmpInst::ICMP_SLT:
|
||||
// Less or equal to zero is not expected.
|
||||
// X < 0 -> Unlikely
|
||||
isProb = false;
|
||||
break;
|
||||
|
||||
case CmpInst::ICMP_UGT:
|
||||
case CmpInst::ICMP_SGT:
|
||||
// Greater or equal to zero is expected.
|
||||
// X > 0 -> Likely
|
||||
isProb = true;
|
||||
break;
|
||||
|
||||
default:
|
||||
} else {
|
||||
return false;
|
||||
};
|
||||
}
|
||||
|
||||
BasicBlock *Taken = BI->getSuccessor(0);
|
||||
BasicBlock *NonTaken = BI->getSuccessor(1);
|
||||
|
Loading…
Reference in New Issue
Block a user